Purification of detergent alkylates

ABSTRACT

HYDROCARBON COMPOUNDS HAVING THE GENERAL FORMULA CNH2N-8, WHERE N IS AN INTEGER FROM ABOUT 10 TO 24, ARE SELECTIVELY REMOVED FROM DETERGENT ALKYLATES BY TREATING THE DETERGENT ALKYLATE WITH AT LEAST 20 PERCENT OLEUM OR SO3 SO AS TO CONVERT CNH2N-8 HYDROCARBON COMPOUNDS TO THEIR ACID DERIVATIVES. THE ACID DERIVATIVES CAN THEN BE SEPARATED FROM THE DETERGENT ALKYLATE.

United States Patent O 3,632,660 PURIFICATION OF DETERGENT ALKYLATES David W. Marshall, Pasadena, Tex., and George C. Feighner, Franklin Lakes, NJ., assignors to Continental Oil Company, Ponca City, Okla. N Drawing. Filed Aug. 9, 1968, Ser. No. 751,387 Int. Cl. C07c 7/00, 3/50 US. Cl. 260-674 A 6 Claims ABSTRACT OF THE DISCLOSURE Hydrocarbon compounds having the general formula C H where n is an integer from about 10 to 24, are selectively removed from detergent alkylates by treating the detergent alkylate with at least 20 percent oleum 0r S0 so as to convert C H hydrocarbon compounds to their acid derivatives. The acid derivatives can then be separated from the detergent alkylate.

BACKGROUND OF THE INVENTION This invention relates to the detergent alkylates. In one aspect this invention relates to a method of selectively removing certain hydrocarbon compound impurities from detergent alkylates.

In another aspect it relates to a method of selectively removing hydrocarbon compounds having the general formula C H- where n is an integer from 10 to 24, from detergent alkylates.

DESCRIPTION OF THE PRIOR ART It is well known to prepare highly effective, watersoluble surfactants by sulfonating the detergent alkylate obtained by alkylating an aromatic compound, usually benzene, with n-chloroparaffins having about 12 to 15 carbon atoms, in the presence of a catalyst, usually aluminum chloride. However, due to the presence of dichloride constituents in the n-chloroparaffins, hydrocarbon compounds represented by the general formula C H where n is an integer from 10 to 24, are produced during the alkylation step of the reaction. The art has become very advanced in the preparation of detergent alkylates, particularly with respect to the sulfonation of the detergent alkylates to prepare surfactants which approach whiteness in color. While the presence of the C H hydrocarbon compounds defined above have no discernible effect upon the surface active properties of the surfactants, nevertheless, good color for these products has become a prime requirement on the part of the manufacturer or formulator of the detergent composition in which these surfactants are prevalently employed.

The manufacturers of detergent alkylates have tolerated the presence of the C H hydrocarbon compounds, such as 1,2,3,4,-tetrahydronaphthalenes, 2,3-dihydroindenes, and phenyl substituted olefins, because of the difficulty required in separating these compounds from the detergent alkylate without the expense of sacrificing undesirable amounts of the detergent alkylate. Further, due to the close boiling points and the like of the C H hydrocarbon compounds with the detergent alkylates and the extensive distillation necessary in order to effectively separate the compounds from the detergent alkylate, it is not feasible to remove the 1,2,3,4-tetrahydronaphthalenes, the 2,3-dihydroindenes, and the phenyl substituted olefins from the detergent alkylate in this manner. Consequently, the detergent alkylates utilized in the industry contain the C H hydrocarbon compounds, which could be classified as impurities.

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SUMMARY OF THE INVENTION The present invention, therefore, resides in the method for selectively removing hydrocarbon compounds having the general formula C H where n is an integer from 10 to 24, from detergent alkylate products prepared by an aluminum halide, such as aluminum chloride or aluminum bromide, catalyzed condensation of a partially chlorinated n-parafiin having about 12 to 15 carbon atoms with an aryl compound, such as benzene. Specifically, this method basically involves the following sequential steps:

(1) Treating the detergent alkylate with up to about 13 weight percent of a treating agent selected from the group consisting of at least 20 percent of oleum and sulfur trioxide in order to convert the C H hydrocarbon compounds to their acid derivatives:

(2) Separating the acid derivatives from the detergent alkylate to recover a detergent alkylate substantially free of the C H hydrocarbon compounds.

OBJECT OF THE INVENTION An object of this invention is to provide a method for selectively removing C H hydrocarbon compounds, such as 1,2,3,4-tetrahydronaphthalenes, 2,3 dihydroindenes, and phenol substituted olefins, from detergent alkylates.

Another object of the invention is to provide a method for selectively removing C,, H hydrocarbon compounds which is effective, economical, and which does not require the consumption of undesirable amounts of the detergent alkylate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In selectively removing hydrocarbon compounds having the general formula C H where n is an integer from 10 to 24, from a detergent alkylate we have now found that the C H hydrocarbon compounds are sulfonated at a faster rate than the detergent alkylate. Thus, by utilizing up to about 13 weight percent of sulfonating agent based on the total weight of the detergent alkylate, and where the sulfonating agent is selected from the group consisting of at least 20 percent oleum and S0 the C H hydrocarbon compounds can be sulfonated and thus removed from the detergent alkylate without appreciable loss of the detergent alkylate. The sulfonated product of the C H hydrocarbon compounds can readily be removed from the detergent alkylate without excessive loss of the detergent alkylate by absorption or neutralization and extraction of the resulting salt with an aqueous-alcoholic wash mixture.

Hydrocarbon compounds which can be readily removed by the process of the present invention and which have the general formula C H where n is an integer from 10 to 24, are generally compounds such as the 1,2,3,4- tetrahydronaphthalenes, 2,3-dihydroindenes, and phenyl substituted olefins. Thus, the following examples are hydrocarbon compounds which are represented by the general formula C H and can be readily removed by the process of the present invention. Such compounds are as follows:

1,2,3 ,4-tetrahydronaphthalene;

l-methyl- 1,2,3 ,4-tetrahydronaphthalene;

6-ethyl- 1,2,3 ,4-tetrahydronaphthalene; 1-propyl-3-ethyl-2,3-dihydroindene; 1,4-diethyl-1,2,3,4-tetrahydronaphthalene; 2-phenyl-1-nonene; 1,2,3,4,5-pentarnethyl-1,2,3,4,S-tetrahydronaphthalene; 1,2,3,4,5,6-hexamethyl-2,3-dihydroindene; 1-methyl-4-heptyl-1,2,3,4-tetrahydronaphthalene; 1-ethyl-4-heptyl-1,,2,3,4-tetrahydronaphthalene;

3 2-isopropyl-3-tertiary butyl-4-ethyl-5-methyl-l,2,3,4-

tetrahydronaphthalene; 1-butyl-4-decyl-1,2,3 ,4-tetrahydronaphthalene; 1-butyl-4-decyl-1,2,3,4-tetrahydronaphthalene; l-pentyl-3-decyl-2,3-dihydroindene; and 5-phenyl-3,7-diethyl-4-tetradecene.

The above examples of the various types of C H hydrocarbon compounds are for illustrative purposes only and it is to be understood that the hydrocarbon compounds desired to be selectively removed from detergent alkylates by the present invention can encompass essentially any and all of the possible compounds which fall within the general formula C H The C H hydrocarbon compounds can be removed from the detergent alkylate by selectively sulfonating the C H hydrocarbon compounds with at least 20 percent oleum or S0 in order to form their acid derivatives and then removing the acid derivative from the unsulfonated detergent alkylate by the use of an absorbent or by neutralization of the acid derivatives and then extraction with an aqueous-alcoholic mixture. The removal of the C H hydrocarbon compounds from the detergent alkylate is possible because the C H hydrocarbon compounds are sul'fonated at a faster rate than the detergent alkylate. However, care must be exercised in controlling the amount of treating or sulfonating agent employed in the sulfonation of the C H hydrocarbon compounds so that the sulfonation of the detergent alkylate is kept at a minimum and thereby allow one to readily separate the sulfonated C H hydrocarbon compounds from the detergent alkylate. It has been determined experimentally that no more than about 13 weight percent of sulfonating agent, based on the total weight of the detergent alkylate, should be employed in the sulfonation of the C H hydrocarbon compounds.

However, one should recognize that the amount of sulfonating agent employed will vary depending upon the level of the C H hydrocarbon compounds present in the detergent alkylate, the level to which the C H hydrocarbon compounds is to be lowered, and the particular type of sulfonating agent employed. For example, when gaseous S0 is employed as the sulfonating or treating agent, the C H hydrocarbon compound content of the detergent alkylate can be lowered from an initial amount, such as about 11 weight percent, to substantially zero by utilizing about 7 weight percent S0 based on the total weight of the detergent alkylate. Further, the S0 employed in the present invention can be in the liquid or gaseous state, although the gaseous state is preferred.

However, when at least 20 percent oleum is employed as the sulfonating agent, the C H hydrocarbon content of the detergent alkylate can be lowered about 50 weight percent by utilizing about 13 weight percent of 20 percent oleum based on the total weight of the detergent alkylate. If more than 13 weight percent of the 20 percent oleum is used in the sulfonation of the C H hydrocarbon compounds, the amount of the detergent alkylate which is sulfonated and thus lost becomes too great and the process is rendered unfeasible. As is apparent from the above discussion, the higher 80;, content of the oleum, the more efficient the separation and the amount of oleum required is reduced. The sulfonation of the C H hydrocarbon compounds with at least 20 percent oleum or S0 can be carried out by any one of a number of sulfonation processes which are well known. However, the temperature during the sulfonation process is maintained in a range of about 20 to 40 C. at substantially atmospheric pressure. Once the C H hydrocarbon compounds have been converted to their acid derivatives by treating the detergent alkylate containing the C H hydrocarbon compounds with at least 20 percent oleum or S0 at a temperature within the range of about 20 to 40 C. and at substantially atmospheric pressure the acid derivatives, and thus the C l-I hydrocarbon compounds, are readily separated from the unsulfonated detergent alkylate by use of an absorbent, such as anion exchange resins, activated carbon, silica gel, diatomaceous earth, and the like. Suitable anion exchange resins are Amberlite IR 1400- a basic anion exchange resin having a basicity of 0.8 meq./gm., manufactured by Rohm & Haas of Philadelphia, Pennsylvania, and Dowex I-X8, an anion exchange resin having a basicity of 2.7 meq./gm., manufactured by Dow Chemical Co., Midland, Mich. Such separation is possible because the acid derivatives of the C H hydrocarbon compounds are absorbed on the absorbent and the purified detergent alkylate substantially free of the acid derivatives of the C H hydrocarbon compounds is recovered from the absorption zone containing the absorbent.

Another method for removing the acid derivatives of the C l-I hydrocarbon compounds from the detergent alkylate when at least 20 percent oleum is utilized as the sulfonating agent comprises neutralizing the acid derivatives and then removing the salts of the C H hydrocarbon compounds so formed with an aqueous-alcohol wash mixture. The neutralizing agent employed is an aqueous solution of ammonium hydroxide or sodium hydroxide. The choice of the neutralizing agent in this method is important because the salts of the C H hydrocarbon compounds must be water soluble in order to provide effective separation of the salts from the detergent alkylate. The percent of sodium hydroxide or ammonium hydroxide present in the aqueous base solution can vary over a wide range. The only criteria is that sufficient alkali be utilized to insure neutralization of the acid derivatives of the C H hydrocarbon compounds. However, desirable results have been obtained where the aqueous-alkali solution contained about 5 to 25 weight percent sodium hydroxide. After neutralization of the acid derivatives of the C H hydrocarbon compounds to form the salt derivatives of same, the detergent alkylate containing the salt derivatives is washed with an aqueous alcoholic mixture in order to remove the salt derivatives of the C H hydrocarbon compounds. Such is readily possible because the sodium and ammonium salt derivatives of the C I-1 hydrocarbon compounds are soluble in the water phase of the wash mixture. The purified detergent alkylate is then dried.

The method for removing the acid derivatives of the C I-I hydrocarbon compounds from the detergent alkylate when is utilized as the sulfonating agent comprises admixing a small amount of Water to the reaction mixture prior to neutralization so that the sulfonic acid hydrides present are hydrolyzed to the sulfonic acid derivatives. The amount of water required to hydrolyze the sulfonic acid anhydrides present will vary but normally about 8 to 15 weight percent, based on the amount of C H- hydrocarbon compounds present in the detergent alkylate, will be sufficient. Once the water has been added, the resulting mixture is then washed with an alcoholicalkali mixture in order to neutralize the acid derivatives and form the salt derivatives of the C H hydrocarbon compounds. The neutralizing agent employed is an aqueous solution of ammonium hydroxide or sodium hydroxide. The percent of sodium hydroxide or ammonium hydroxide present in the aqueous solution can vary over a wide range, and the only criteria is that suflicient alkali be employed to neutralize substantially all of the acid derivatives of the C H hydrocarbon compounds. Desirable results have been obtained where the precent of alkali present in the aqueous solution ranges from about 5 to 25 weight percent. As previously stated, it is important that sodium hydroxide or ammonium hydroxide be employed as the neutralizing agent because the sodium and ammonium salt derivatives of the C H hydrocarbon compounds are soluble in Water and thus can readily be separated from the detergent alkylate.

The alcohol used in the aqueous-alcoholic wash mixture or the aqueous-alkali alcoholic wash mixture described above can be any suitable alcohol, such as ethanol, n-propanol and isopropanol, and the ratio of the alcohol to water constituents can vary over a wide range. However, care must be exercised to provide enough water in the mixture to dissolve substantially all of the salt derivatives of the C H hydrocarbon compounds. Thus, it is preferred that the mixture contain at least about 30 volume percent water, and preferably at least 50 volume percent.

In order to illustrate further to those skilled in the art the nature of the present invention and how it can be practiced, the following examples are given. As indicated, these examples are set forth primarily for the purpose of illustration and, accordingly, any enumeration of details contained therein should not be interpreted as a limitation on the invention except as such are expressed in the appended claims.

Example I A sample of crude detergent alkylate reaction product mixture obtained by the aluminum chloride catalyzed alkylation of benzene with partially chlorinated C -C normal paratfins and containing about 7.2 weight percent C I-I hydrocarbon compounds was reacted with varying amounts of 20 percent oleum. The reaction was carried out at room temperature, i.e., about 25 C., under atmospheric pressure. The 20 percent oleum was added to a stirred flask containing the detergent alkylate reaction product mixture. Following the addition of the 20 percent oleum, the resulting treated mixture was stirred for an additional 20 to 30 minutes. No temperature rise was detected during the addition of the 20 percent oleum or the subsequent stirring period. The treated mixture was then separated from any sludge which formed during the addition of the 20 percent oleum and the subsequent stirring period. The treated mixture was then neutralized with a 5 percent by weight aqueous sodium hydroxide solution and washed with a 50/50 volume mixture of water and isopropanol. The washed, treated detergent alkylate was then dried by filtering the same through diatomaceous earth. The dried detergent alkylate was then analyzed for C H hydrocarbon compounds and the liquid wash phase was analyzed to determine the percent detergent alkylate (monoalkylate) lost during the treatment of the crude detergent alkylate reaction product. The table below contains the results of the analysis and all percentages are by weight.

Percent c l'h -g Thus, it is readily apparent that by employing 20 percent oleum the C H hydrocarbon compounds in the crude detergent alkylate reaction product mixture are sulfonated at a faster rate than the detergent alkylate. Further, by employing 13 Weight percent of the 20 percent oleum, approximately 50 percent of the C H hydrocarbon compounds can be removed from the detergent alkylate. However, care must be exercised in not exceeding the 13 weight percent of the 20 percent oleum because when one exceeds this amount of 20 percent oleum the loss of detergent alkylate due to the treatment becomes too great.

Example II A sample of crude detergent alkylate reaction product mixture obtained by the aluminum chloride catalyzed alkylation of benzene with partially chlorinated C -C normal paratlins and containing about 11 weight percent C H hydrocarbon compounds was reacted with varying amounts of diluted gaseous S0 The crude detergent alkylate was placed in a tubular reactor having a 3-inch diameter. The temperature of the crude detergent alkylate was about 25 C., i.e., room temperature, and this temperature was maintained throughout the reaction. The gaseous S0 was added to the crude detergent alkylate in the tubular reactor by employing a syringe pump. Air was utilized to dilute the S0 and the flow rate of the air was 20 liters of air per minute. After the diluted S0 was introduced into the tubular reactor, the was allowed to contact the detergent alkylate for 30 minutes. The reaction mixture was then withdrawn from the tubular reactor and admixed with one Weight percent water. The resulting mixture was then washed with a 50/50 by volume isopropanolic and a 5 percent by weight sodium hydroxide mixture. The washed detergent alkylate was then dried and analyzed for C H hydrocarbon compound content and the wash solution was analyzed to determine the. percentage of detergent alkylate (monoalkylate) lost during the treatment of the crude detergent alkylate reaction product. The table below contains the results of the anal ysis and all percentages are by weight.

Percent CnHz Thus, it is readily apparent that by employing gaseous S0 the C H hydrocarbon compounds in the crude detergent alkylate reaction product mixture are sulfonated at a faster rate than the detergent alkylate. Further, by employing about 7 weight percent gaseous S0 substantially all of the C H hydrocarbon compounds can be removed from the detergent alkylate without any appreciable loss of the detergent alkylate.

The reduction of the amount of C H hydrocarbon compounds present in a crude detergent alkylate is clearly illustrated by the above examples. Further, in order to prevent an excessive loss of the detergent alkylate and, at the same time, provide an effective method for removing or reducing the C H hydrocarbon compounds from a detergent alkylate, it is clearly shown that one must employ at least 20 percent oleum or S0 as the treating agent and the amount of the treating agent must be controlled.

Having thus described the invention, we claim:

1. A method for selectively removing hydrocarbon compounds having the general formula C H where n is an integer from 10 to 24, from a detergent alkylate comprising:

'(a) treating said detergent alkylate with up to about 13 weight percent of at least 20 percent oleum for a sufficient period of time to convert said hydrocarbon compounds to their acid derivatives;

(b) neutralizing the treated material of step (a) with an aqueous-alkali mixture which contains about 5 to 25 weight percent alkali selected from the group consisting of sodium hydroxide and ammonium hydroxide in an amount sufiicient to form a neutralized mixture containing salt derivatives of said C H hydrocarbon compounds;

(C) washing said neutralized mixture with an aqueous alcohol mixture containing at least 30 volume percent water to remove said salt derivatives; and

(d) drying said detergent alkylate and recovering a purified detergent alkylate.

2. The method of claim 1 wherein said aqueous alcohol mixture contains about 50 volume percent Water.

3. The method according to claim 2 wherein the alcohol constituent of said aqueous-alcohol mixture is selected from the group consisting of ethanol, n-propanol, and

isopropanol.

4. A method for selectively removing hydrocarbon compounds having the general formula C H wherein n is an integer from 10 to 24, from a detergent alkylate comprising:

(a) treating said detergent alkylate with from about 1 to about 7 weight percent sulfur trioxide for a sufficient period of time to convert said hydrocarbon compounds to their sulfonic acid hydrides formed during the treating of said detergent alkylate with said sulfur trioxide;

(b) admixing an effective amount of Water with the product of step (a) to hydrolyze said sulfonic acid hydrides formed during the treating of said detergent alkylate with said sulfur trioxide;

(c) Washing the mixture of step (b) with an aqueous alkali alcohol mixture wherein the alkali constituent of said mixture is present in an amount of from about 5 to 25 Weight percent and said alkali constituent is selected from the group consisting of sodium hydroxide and ammonium hydroxide, said mixture being employed in an amount at least sufficient to convert said hydrolyzed components of step (b) 6. The method of claim 5 wherein said Water required I to hydrolyze said sulfonic acid hydrides is present in an amount of about 8 to 15 weight percent based on the amount of C H hydrocarbon compounds present in said detergent alkylate.

References Cited UNITED STATES PATENTS 2,688,633 9/1954 Cohen 260674 2,843,626 7/1958 Gebelein et al. 260-671 2,932,677 4/1960 Kirk et al 260-674 DELBERT El GANTZ, Primary Examiner C. E. SPRESSER, JR., Assistant Examiner US. Cl. X.R. 260671 B 

